Question

The vapour density of a gas is 40. Calculate the volume of 20g of this gas at 27°C and 950 mmHg pressure.

Answer 1

Given,

V.D = 40

Molar Mass = 40/2

= 20 g

Mass Given = 20 g

No. of Mole = 20/20

= 1

1 Mole of any Gas at S.T.P contains 22.4 L,

At S.T.P,

Volume 1 (V₁) = 22.4 L

Temperature 1 (T₁) = 273 K

Pressure 1 (P₁) = 760 mm of Hg

Temperature 2 (T₂) = 300 K

Pressure 2 (P₂) = 950 mm of Hg

By Ideal Gas Equation,

P₁V₁/T₁ = P₂V₂/T₂

= (760*22.4)/273 = (950*V₂)/300

= 17024/273 = 950V₂/300

= (17024*300)/(273*950) = V₂

= 19.69 L = V₂

The New Volume will be 19.69 L.

I hope this helps.